awhile back i bought a th350 trans with a 203 t case attached to it. i ended up giving the 203 away cuz i dont care for those t cases. 2wks ago i picked up a truck to part out so i had another motor for my muddin truck. anyways it had a 4spd manual with granny gear and a 205 t case attached to it. now what would have to be done to either or both the 205 and the th350 trans to make them work together? my original plan was to get a diff tail shaft and adaptor plate and run a 208 t case but sense i have a 205 i may change my mind and run that but i dont know what is needed to make the 205 work on the 350 trans.
thanks for any help
Depends on how you want to use it, how your set up too..
gear ratios are different between the 2 cases, 208 will allow for use of 2nd gear in a bogger with 40's, 4:10's, and 350ci.
I have a 355ci/205, 4:10's and 40's.. I have to run 1st gear to keep em spinning, I hit 2nd and motor boggs down. but my t/case is bullet proof..
when I change to my 36" tires, all's good.
as far as what you need.. adapter plate and shaft (its a little splined tube that connects trans output with t-case input), you will also need the t-case support mount, it bolts to your t-case and frame rail and has rubber/poly bushings.
if your 205 if off a 4 speed it would hook to a 400th... if I was you I would run a 208 I got one now and love it and will never change it.. if you want a 350th to a 205 I for everything you need adaptor coupling and tcase I may sell! but remember a 205 has a 1.96 low and a 208 has 2.62 (something like that)
well wouldn't you need to change the whole shaft in a 350t to use a 208?
you cant use the output shaft that was used on a 203 for a 208 cause its too short! you need a medium shaft 350th.
offroaddesign.com sells them shafts...i think
i was going ot buy the stuff i need to make the 208 work with my 350trans right from advanced adaptors. the 350trans i have had a 203 hooked to it so if i read that right ill beable to hook the 205 right to the trans as is becuase i do have that splined tube which was used with the manual trans.
if so thats where im stuck. do i want to rebuild the trans the way i want and run the 205 or when i rebuild the trans throw in the diff tail shaft and use the 208. i have 2 208 t cases laying around so im not worried about buying one if i break it.
You didnt say what Year your NP205 came out of, they offered 2 different rear splines on those........the 1968-1980 for SM465 4spd............and in 1981 they went to a long shaft 32 spline rear (which is the same as 400 turbo)
The 68-80 Sm465 NP205 has a thick but stubby 10 spline shaft............the 81 up has a long 32 spline shaft...........if you have the early 10 spline 205 you wont be able to use your 4spd 205 on a 350 turbo................you need one that was already bolted to a 350 turbo.
The Np208 idea is one that I played hell with myself.............the only year GM offered the NP208 behind the 350 turbo was the 1981 model year..........making it very rare to find one. The reason you can't bolt a 81-up NP208 behind 99% 350 turbos is because the 1970-1980 4x4 350 turbo was only set up to run the Np205, and NP203 and it used a short tailshaft on it ( hence the short flat 203 adaptor plate.....and splined coupler that the 205 uses inside its adaptor).
So you have to consider whats going to be easier and cheaper for you.................find and buy a Np205 with adaptor & coupler ready to bolt up to your trans......................or since your rebuilding your trans..................while apart, install the 2wd 350 turbo shaft and run a spacer in order to use your Np208.
205's are super strong...........but lack the low range gearing that a 208 can give ya, but 208's are alot easier/cheaper to find than Np205's that were behind auto tranny's.
i never new that but that was very informative. as for the 205 it came out of a 1978 chevy truck so it does have that 10 spline shaft. as it looks im going to run the 208 i have. i called advanced adaptors and talked to them awhile back about it and they have a kit made just for bolting a 208 to a 350 trans so i have a feeling that is the way im going to go now.
thanks for all the help everyone. i really appreciate it
was just on advanced adapters website. they do offer the diff output shaft for the 350 trans that has the 10 spline count on it so it would work with the 205 for 276.00. or i can replace the output shaft on the trans to use a 208 which will cost me 200.00. and sense i have 2 208 t cases i think i might end up going that route and sell the 205.
so anyone interested in picking up a 205 t case if i decide to sell it? lol if i do sell it that helps me get that much closer to getting my trans done i never drove the truck but i do know the guy i bought hte truck off of and the truck moved and drove perfect. 4wd worked perfect to. only reason he parked the truck before i bought it was the body was shot on it but the drive train was still in great working condition.